Bulb socket

Abstract: A bulb socket mounted on a partition wall of a lamp house through an elastic gasket, for receiving a bulb and electric terminals, comprises a front casing and a rear casing. The front casing (1) which is receiving a proximal end portion of the bulb has engagement projections (14) on an outer periphery thereof. The rear casing (2) has a mounting flange (22) on an outer periphery thereof for holding the partition wall (21) of the lamp house with the engagement projections (14) of the front casing. The rear casing (2) is molded separately from the front casing (1) by a mold which allows the rear casing (2) to be removed therefrom in an axial direction. The front casing (1) and the rear casing (2) are integrally joined at their open end surfaces.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a bulb socket for being attached to a lamp house. 2. Description of Prior Art As shown in Figs. 5 and 6, a socket casing 50 of a conventional bulb socket according to the first part of claim 1 is integrally molded of a resin, and includes a tubular socket portion 51 for receiving a bulb, and a tubular connector portion 52 extending from this socket portion. An outwardly-extending, mounting flange 53 of a larger diameter is formed on an outer peripheral surface of the socket casing 50 at the boundary between the socket portion 51 and the connector portion 52. And engagement projections 54 are formed on the outer peripheral surface of the socket portion. A plate-like finger support 56 is formed on and projected from the outer peripheral surface of the connector portion 52. For attaching the bulb socket of this construction to a lamp house, the socket portion 51 is passed through a mounting hole 61 formed through a partition wall 60 of the lamp house, with a gasket 62 of an elastic material interposed between the mounting side of the mounting flange 53 and the partition wall, thus compressing the gasket 62 hard, and in this condition the socket is turned by putting the finger on the finger support portion 56, so that the partition wall 60 is held between the engagement projections 54 and the partition wall 60. The gasket 62 is elastically pressed against the partition wall 60 and the mounting flange 53, thereby imparting waterproofness to the interior of the lamp house. The mounting flange 53, extending over the entire circumference, and the plurality of engagement projections 54 need to be formed on the outer periphery of this conventional socket casing in axially spaced relation to each other. Therefore, it is difficult to remove the socket casing 50 from a mold in the axial direction, and therefore the socket casing is molded by a molding method in which the socket casing is removed from the mold in a direction perpendicular to the axis thereof, which mold can be split into halves in the axial direction. As a result, as shown in an exaggerated manner in Figs. 5 and 6, axially-extending, linear protuberances, called parting lines P, are formed respectively on upper and lower portions of the outer periphery of the socket casing 50. These raised parting lines P extend across a press surface of the mounting flange 53 which is pressed against the gasket 62, and therefore the gasket 62 can not be held in intimate contact with the mounting flange along the parting lines P, thus inviting a problem that the sealing performance achieved by the gasket 62 is affected. For attaching a bulb to the bulb socket, a mounting groove 63, called a J-slot, is formed in the inner peripheral surface of the socket portion. This J-slot 63 has an axially-extending insertion groove 63a, and an engagement groove 63b extending laterally perpendicularly from a distal end of the insertion groove 63a. One side surface of the engagement groove 63b disposed at the insertion side serves as an engagement portion 63c. In order to form the J-slot 63 having the laterally perpendicularly-extending engagement groove 63b, a complicated molding method as disclosed in Japanese Patent Unexamined Publication No. 61-96684 must be used. Further, US-A-0,397,972 discloses a lamp socket assembly comprising a housing and a body which is inserted in the housing and welded thereto. A flange seal is seated on a mounting flange and seals that flange and therefore the entire lamp socket assembly to an automobile panel. However, the assembly includes a contact insert which is arranged within the body and the housing for receiving the lamp thereby raising the costs for production and assembly. Additionally, there are specific requirements for the assembly of the body to the housing by energy directors rendering it doubtful whether a proper joint between both parts can be achieved. Moreover, US-A-3,800,267 discloses lamp sockets of particular utility with automatic vehicles in sheltered places when the need for weather-proofing is minimal and where moisture seal is not required. However, the lamp socket comprises a socket body in which a bulb insert unit is inserted that has a J-slot formed in the inner surface of the bulb insert unit. Further the bulb insert unit is completely surrounded by the socket body and snapped to the inner surface of the socket body. It is therefore an object of the present invention to provide a bulb socket which has a good sealing performance. It is another object of the invention to provide a bulb socket which can be produced by a mold of a simple construction. SUMMARY OF THE INVENTION In order to achieve the object, the invention provides a bulb socket according to claim 1 mountable on a partition wall of a lamp house through an elastic gasket, for receiving a bulb and electric terminals, the bulb socket comprising a front casing and a rear casing. The front casing which is receiving a proximal end portion of the bulb has engagement projections on an outer periphery thereof. The rear casing has a mounting flange on an outer periphery thereof for holding the partition wall of the lamp house with the engagement projections of the front casing. The rear casing is molded separately from the front casing by a mold which allows the rear casing to be removed therefrom in an axial direction. The front casing and the rear casing are integrally joined at their open end surfaces. The front casing, molded separately from the rear casing, is removed from an associated mold in an axial direction, and a J-slot is formed in an inner surface of the front casing, and the J-slot is formed by an insertion groove and a engagement groove which axially linearly extend respectively from left and right open ends of the front casing in offset relation to each other, and a mounting pin projected from an outer periphery of the bulb can be received in the J-slot, and then the bulb can be turned so as to retainingly engage the mounting pin in the J-slot. The socket casing is formed by molding the front casing and the rear casing separately from each other. The mounting flange is formed on the outer surface of the rear casing preferably over the entire circumference, and is projected preferably in a direction perpendicular to the axial direction. There is no obstructive portion which prevents the removal of the rear casing from the mold in the axial direction, and therefore the rear casing can be molded by a molding method in which the rear casing is allowed to be removed from the mold in the axial direction. Then, an axially-extending, parting line is not formed on the outer surface of the rear casing, and when the bulb socket, formed by integrally joining the rear casing and the front casing together, is mounted on a partition wall of a lamp house, a gasket is held in intimate contact with the mounting flange over the entire peripheral portion, thereby achieving a sealing effect. The J-slot is formed with the insertion groove and the engagement groove axially linearly extending respectively from the left and right open ends of the front casing in offset relation to each other, and therefore the front casing can be molded by a mold of a simple construction. As described above, according to the invention, the front casing and the rear casing are molded separately from each other, and the two casings are integrally joined together at their open end surfaces. Therefore, the rear casing can be molded by the mold of a simple construction which can be split in the axial direction. As a result, a radially-extending parting line is not formed on the sealing surface of the mounting flange, thereby providing the bulb socket having an excellent sealing performance. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of a socket casing in a separated condition; Fig. 2 is a vertical cross-sectional view of a front casing; Fig. 3 is a vertical cross-sectional view of a rear casing; Fig. 4 is a perspective view of the socket casing ; Fig. 5 is a perspective view of a conventional socket casing; and Fig. 6 is a vertical cross-sectional view of the conventional socket casing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One preferred embodiment of the present invention will now be described with reference to the drawings. As shown in Fig. 1, a socket casing of this embodiment includes a front casing 1 and a rear casing 2 which are separately molded of a resin by respective molds. The front casing 1 is of a double-tube construction, and two insertion grooves 12 of a generally T-shaped cross-section (in which feeder terminals (not shown) for connection to a base of a bulb are mounted) are symmetrically formed in an inner surface of an inner tube 11. As shown in Fig. 2, each insertion groove 12 extends linearly between opposite (right and left) open ends of the inner tube. A J-slot 13 for the purpose of attaching the bulb is formed in the inner peripheral surface of the inner tube 11 at a position angularly spaced about 90° from the insertion grooves 12. As shown in Fig. 2, the J-slot 13 has an insertion groove 13a extending linearly inwardly from the left open end, and a engagement groove 13b extending linearly from the right open end, the two grooves 13a and 13b being continuous with each other in an offset manner. This offset portion provides a retaining portion 13c extending perpendicularly from the distal end of the insertion groove extending linearly from the left open end. Four engagement projections 14 are formed on the outer peripheral surface of the front casing 1, and are spaced circumferentially at generally equal intervals. An annular welding projection 15 is formed on the right open end surface in surrounding relation to the end opening. The front casing 1 is formed by a mold which is split into right and left portions at a region where the engagement projections 14 are formed, and allows the removal of the molded casing in the axial direction. The front casing 1 has no portion which must be removed from the mold in a direction perpendicular to the axial direction, and therefore the front casing is molded by the mold of a simple construction. Therefore, even though a parting line is formed at the mating surface between the right and left mold portions, this parting line extends from the engagement projections 14 in a direction perpendicular to the axis, as shown in an exaggerated manner in Fig. 1. As shown in Fig. 3, the rear casing 2 comprises a tube having a partition wall 21 formed therein, and a mounting flange 22 of a larger diameter is formed on an outer periphery of the rear casing at a left open end thereof. A left half 23 of the tube having the mounting flange 22 is equal in inner diameter to the front casing 1, and a right tube half 24 is formed into a hood-like structure for receiving a female connector (not shown). A plate-like finger support 25 is formed on and projected from the outer periphery of the rear casing 2, and extends in the axial direction. Insertion grooves 26 are formed axially in the inner peripheral surface of the tube half 23, and are continuous respectively with the insertion grooves 12 in the front casing 1, and have the same cross-sectional shape as that of the insertion grooves 12. Each feeder terminal is inserted into the associated insertion groove 26 through the associated insertion groove 12, and extends through an insertion hole 27, formed through the partition wall 21, into the tube half 24, so that the distal end portion of the feeder terminal extending into the tube half 24 serves as a male metal terminal. Also formed through the partition wall 21 is an insertion hole 28 into which a male metal terminal, connected to an end of a spring (not shown) resiliently urging a contact of the bulb, is inserted. In this connector portion, the male metal terminals are projected respectively through the two insertion holes 27 and 28, and are to be fitted respectively on female metal terminals (not shown). A peripheral edge portion of the left open end of the rear casing 2 is slightly recessed from the surface of the mounting flange 22 to provide a joint surface 22a which is joined to the welding projection 15. The rear casing 2 is formed by a mold which is split into right and left portions, with a mating surface disposed at the left surface of the mounting flange 22, and allows the removal of the molded casing in the axial direction. Except for a narrow portion between the mounting flange 22 and the finger support 25, the rear casing 2 has no portion which must be removed from the mold in a direction perpendicular to the axial direction, and therefore the rear casing can be molded by the mold of a simple construction. Therefore, a parting line will not be formed on the left surface of the mounting flange 22 by the mating surface between the right and left portions of the mold for molding the rear casing 2. The front casing 1 and the rear casing 2 are thus molded separately from each other, and the insertion grooves 12 are aligned with the insertion grooves 26, respectively, and the welding projection 15 of the front casing is abutted against the joint surface 22a of the rear casing, and then is fusingly bonded thereto by heating, thereby forming the socket casing of an integral construction shown in Fig. 4. Thereafter, the feeder terminals and so on are inserted and attached to provide the bulb socket. For attaching the thus formed bulb socket of this embodiment to a partition wall of a lamp house, the parting line P as in the conventional construction is not formed on the mounting flange 22 pressed against a gasket, and therefore the gasket can be attached to the mounting flange 22 in intimate contact therewith, thereby achieving a sealing effect. In this embodiment, not only the rear casing 2 but also the front casing 1 are formed by the respective molds of the right-left split type, and therefore the J-slot can be formed by the insertion groove 13a and the engagement groove 13b which linearly extend respectively from the left and right open ends in offset relation to each other in the tube, and therefore there is no need to use a mold of a complicated construction as disclosed in Japanese Patent Unexamined Publication No. 61-96684, and the molding can be carried out using the molds of a simple construction.

Claims: A bulb socket mountable on a partition wall (60) of a lamp house through an elastic gasket (62), for receiving a bulb and electrical terminals, said bulb socket comprising: a front casing (1) for receiving a proximal end portion of the bulb, said front casing (1) having engagement projections (14) on an outer periphery of said front casing (1) and a J-slot (13) formed in an inner surface of said front casing (1), said J-slot (13) being defined by an insertion groove (13a) and an engagement groove (13b) which axially linearly extend in offset relation to each other, said J-slot (13) for receiving a mounting pin projected from an outer periphery of the bulb in said J-slot (13) and for retainingly engaging the mounting pin; and a rear casing (2) having a mounting flange (22) on an outer periphery of said rear casing (2), said mounting flange (22) shaped to hold the partition wall (60) of the lamp house with said engagement projections (14) of said front casing (1), characterised in that said front casing (1) is molded separately from said rear casing (2) such that said J-slot (13) the insertion groove (13a) and the engagement groove (13b) of which extending respectively from left and right open ends of said front casing (1) allows said front casing (1) a removal from molds in an axial direction, and that a parting line (P) between the molds is formed perpendicular to the axial direction; and said front casing (1) and said rear casing (2), being integrally joined at open end surfaces (22a) by welding after molding, said front casing (1) and said rear casing (2) jointly forming said bulb socket. Bulb socket according to claim 1, characterised by feeder terminals mounted in said tubular front casing (1) and in said tubular rear casing (2), said feeder terminals feeding electric power to said bulb, wherein said rear casing (2) is molded (2) separately from said front casing (1) by a mold which allows said rear casing (2) to be removed therefrom in an axial direction. Bulb socket according to claim 1 or 2, characterised by said J-slot, which is defined by said insertion groove (13a) and said engagement groove (13b) in such an offset relation that an offset portion between said insertion groove (13a) and said engagement groove (13b) provides a retaining portion (13c) extending perpendicularly from said insertion groove (13a) and said engagement groove (13b), for receiving a mounting pin projected from an outer periphery of said bulb wherein the bulb is turned so as to retainingly engage said mounting pin in said J-slot (13).

Inventors: SAWADA HISASHI, SAWADA, HISASHI,                               TD., SAWADA, HISASHI, C/O SUMITOMO WIRING SYSTEMS, LTD.
Applicants: SUMITOMO WIRING SYSTEMS, SUMITOMO WIRING SYSTEMS, LTD.
Application year: 1994
Main classification: H01R33
IPC codes: H01R33, H01R13